1. Field of the Invention
The present invention relates to an ultrasound diagnosis apparatus including a main unit and an ultrasound probe, which is connectable to the main unit.
2. Discussion of the Background
Ultrasound diagnosis apparatuses are generally used in a medical field. An ultrasound diagnosis apparatus transmits ultrasound signals from its ultrasound probe towards a patient and receives echo signals resulting from the ultrasound signals from the patient so that ultrasound image data can be prepared based on the echo signals. Doctors diagnose ultrasound images displayed based on the ultrasound image data with respect to the patient. There are many types of ultrasound probes according to diagnostic purposes, such as, for example, which part to diagnose and in what condition the patient is. One of the ultrasound probes which is appropriate for a specific purpose may selectively be used by switching the ultrasound probes connected to a main unit of the ultrasound diagnosis apparatus. Each ultrasound probe is detachable from the main unit through connectors. For example, when three ultrasound probes are connected to the main unit, one desired from the three ultrasound probes is made usable by the doctor's operating one or more switches provided in the main unit.
An ultrasound probe electrically connected to the main unit may be called an active ultrasound probe. An ultrasound probe which is not electrically connected to the main unit but ready for use may be called a standby ultrasound probe. An ultrasound probe which may not be used relatively so often can be the standby ultrasound probe and be replaced with the active ultrasound probe, if necessary.
FIG. 1A is an illustration showing a front view of the first conventional ultrasound diagnosis apparatus. FIG. 1B is an illustration showing a side view of the first conventional ultrasound diagnosis apparatus. Similarly, FIG. 2A is an illustration showing a front view of the second conventional ultrasound diagnosis apparatus. FIG. 2B is an illustration showing a side view of the second conventional ultrasound diagnosis apparatus. The difference between the first and second conventional ultrasound diagnosis apparatuses is an arrangement of connectors for ultrasound probes as will be described below.
An ultrasound diagnosis apparatus 1 includes casters 2, a main unit 3, an ultrasound probe 4 (shown in FIG. 3), an operation panel 5, a display unit 6, and a cable hanger 7. The main unit 3 is allowed to move with the casters 2. The main unit 3 receives echo signals from the ultrasound probe 4 and processes the echo signals so as to obtain ultrasound images. The main unit 3 has a plurality of main unit connector 3a (e.g. three main unit connectors 3a) along a horizontal direction of the main unit 3 as shown in FIGS. 1A and 1B or along a vertical direction of the main unit 3 as shown in FIGS. 2A and 2B. The three main unit connectors 3a are electrically connected to a circuitry board provided in the main unit 3. There is a plurality of the ultrasound probe 4 (e.g. three ultrasound probes 4). When the three ultrasound probes 4 are connected to the three main unit connectors 3a, one of the three ultrasound probes 4 can selectively be activated through the circuitry board and one of the main unit connectors 3a. 
Each ultrasound probe 4 can be used to transmit ultrasound signals and receive echo signals resulting from the ultrasound signals. As shown in FIG. 3, the ultrasound probe 4 includes an ultrasound probe head 4a, an ultrasound probe connector 4b, a cable 4c, a connector fixing tab 4d, and a connection pin 4e. The ultrasound probe head 4a includes a plurality of ultrasound transducers to transmit ultrasound signals (or ultrasound pulses). The ultrasound transducers are also used to receive echo signals resulting from the ultrasound signals. The ultrasound probe head 4a is connected to the ultrasound probe connector 4b through the cable 4c. The ultrasound probe connector 4b can be connected to the main unit connector 3a provided in the main unit 3 when the ultrasound probe 4 is used as an active ultrasound probe. The connector fixing tab 4d is used to fix the ultrasound probe connector 4b to the main unit connector 3a when the ultrasound probe connector 4b is connected to the main unit connector 3a. The connection pin 4e is inserted into a connection hole provided in the main unit connector 3a when the ultrasound probe connector 4b is connected to the main unit connector 3a. 
The operation panel 5 is provided at the upper part of the main unit 3 and used to input information, instructions, and the like. The operation panel 5 has a probe head holder 5a to hold the ultrasound probe head 4a. The display unit 6 is provided on the top of the main unit 3 and used to display ultrasound images. The cable hanger 7 is provided to hang a part of the cable 4c at a higher position than the probe head holder 5a. The cable hanger 7 can be inflected or bended so as to hang the cable 4c at a desired height. In FIGS. 1A to 2B, the cable hanger 7 hangs the cables 4c of the three ultrasound probes 4. There may be one or more standby ultrasound probes which may be placed at other position than the ultrasound diagnosis apparatus 1.
Another ultrasound diagnosis apparatus has been introduced as described in Japanese patent application publication No. 2003-339702 which may correspond to U.S. patent application publication No. 2003/0217600. In this ultrasound diagnosis apparatus, a main unit connector to be connected to an ultrasound probe connector is provided at a position between a main unit and a display unit.
The conventional ultrasound diagnosis apparatuses have the following problems or defects.
The ultrasound diagnosis apparatus has been required to improve image resolution. To meet this requirement, the ultrasound probe head 4a has more and more channels, that is, a number of ultrasound transducers provided in the ultrasound probe head 4a including, for example, piezoelectric transducers. The number of channels affects the number of signal pins provided at a face of the ultrasound probe head 4a where the ultrasound probe connector 4b is connected to the main unit connector 3a. Therefore, the more the number of channels increases, the larger the ultrasound probe head 4a becomes. Further, a three-dimensional ultrasound scan has been introduced recently, which is accomplished by an ultrasound probe having ultrasound transducers two-dimensionally arrayed at an ultrasound probe head. In such an ultrasound probe, the number of channels significantly increases, compared to an ultrasound probe including one-dimensionally arrayed ultrasound transducers. Therefore, the ultrasound probe connector becomes larger and a cable connected to the ultrasound probe connector becomes thicker.
Meanwhile, the main unit 3 has recently been required to be more compact and lighter-weight so as to be easily moved and to occupy less space. This requirement limits the number of main unit connectors 3a and flexibility of a layout of the main unit connectors 3a. Particularly, this is a problem when the ultrasound probe 4 has a larger size of the ultrasound probe connector 4b. In other words, it is hard to make the main unit 3 compact if the desired number of ultrasound probe connectors 3a are provided in the main unit 3 and/or the ultrasound probe head 4a has more channels.
Further, when the standby ultrasound probe is placed at other position than the ultrasound diagnosis apparatus 1, it is not easy to immediately replace the active ultrasound probe with the standby ultrasound probe, which results in a waste of time in an ultrasound imaging examination.
When the ultrasound probe connectors 4b are connected to the main unit connectors 3a as shown in FIGS. 1A and 2A, the cables 4c may be lead out from the ultrasound probe connectors 4b to be pulled towards the cable hanger 7 at about right angle particularly when the cables 4c are thick and rigid like the ultrasound probe including the two-dimensionally arrayed ultrasound transducers. Alternatively, the cables 4c may sag a little and be pulled towards the cable hanger 7. In either way, the cables 4c are given a strong effort in the vicinity of the ultrasound probe connectors 4b, which may lead to a wire break in the cables 4c. Particularly, when the cables 4c are thick and rigid, the moment of force given to the cables 4c in the vicinity of the ultrasound probe connectors 4b may become too large so that the cables 4c may be damaged. In addition, when the doctor brings the ultrasound probe connector 4b so as to connect it to the main unit connector 3a, the strong tension of the cable 4 is effected to the doctor's hand and arm. This may result in deteriorating the operationality of connecting the ultrasound probe connector 4b. 
Still further, when the circuitry board is provided in parallel with the three main unit connectors 3a, the signal transmission distance between the circuitry board and the ultrasound probe connector 4b connected to the main unit connector 3a differs among the main unit connectors 3a. This may cause the echo signals received from the ultrasound probe 4 to be different in their characteristics.
Further, the circuitry board is typically provided in the middle of or in the lower part of the main unit 3. Therefore, when it is the ultrasound diagnosis apparatus described in the above-mentioned Japanese patent application publication, the signal transmission distance between the circuitry board and the main unit connector is so long that noise signals may be generated in the echo signals received from the ultrasound probe 4 and deteriorate ultrasound image quality. In addition, since the main unit connector is provided at a rather high position of the ultrasound diagnosis apparatus, dragging about the cable may disturb the doctor's operation of the ultrasound diagnosis apparatus.